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Abstract
We report a new flow control method for centrifugal microfluidic systems; CO2 is released from on-board stored baking powder upon contact with an ancillary liquid. The elevated pressure generated drives the sample into a dead-end pneumatic chamber sealed by a dissolvable film (DF). This liquid incursion wets and dissolves the DF, thus opening the valve. The activation pressure of the DF valve can be tuned by the geometry of the channel upstream of the DF membrane. Through pneumatic coupling with properly dimensioned disc architecture, we established serial cascading of valves, even at a constant spin rate. Similarly, we demonstrate sequential actuation of valves by dividing the disc into a number of distinct pneumatic chambers (separated by DF membranes). Opening these DFs, typically through arrival of a liquid to that location on a disc, permits pressurization of these chambers. This barrier-based scheme provides robust and strictly ordered valve actuation, which is demonstrated by the automation of a multi-step/multi-reagent DNA-based hybridization assay.
Highlights
Over the past decade, centrifugal microfluidic systems [1,2,3] have been applied to a variety of application fields such as biomedical diagnostics [4,5,6], bioprocess monitoring [7] and environmental screening [8,9,10]
As all liquids on-disc are subjected to the same centrifugal field, advanced valving schemes are required to automate a sequences of laboratory unit operations (LUOs) such as mixing, metering and reagent release [13]
In the second approach, called “barrier governed”, we demonstrate how the disc can be divided into discrete chambers that are separated by dissolvable films
Summary
Over the past decade, centrifugal microfluidic systems [1,2,3] have been applied to a variety of application fields such as biomedical diagnostics [4,5,6], bioprocess monitoring [7] and environmental screening [8,9,10]. Recently introduced valving class [35,36], the arrival of liquid in a designated location triggers the subsequent valving steps In this so-called event-triggered flow control, the layout of the disc-based channel network, rather than changes in disc spin rate, fully determines the order in which valves actuate. As event-triggered valves operate essentially independent of the spin rate, the number of assay steps that can be automated on a disc is not restricted by the finite spin rate envelope These valves can result in a relatively large reagent and sample loss due to the dead volume of these valves. OOnnllyy tthhee ggaass ppoocckkeettaatttthheeddisissosolvlvabalbelefilfimlm(D(DF)Fm) memebmrabnraenies is expexopseodsetdo ttohethheydhryodsrtoastitcatpicrepsrseusrseuhreeahdeaodf tohfetuhpe sutrpesatmreasmamspamlep; (lbe;) (ubp)ounpsopninsnpiinnngi,nagc,aapiclalapriyllabruyrst vthaeltpbvhunreeeressoststwapumveroianprslkselveseaaptnnhroddoepttetnrhhnueeustdwseaasoncnroicdnkimltlaotaphnrtredhyeestalshipnqeuncsusieltilucdhaomermryeagpatalircicsqehcspuehsiosedacsmtkhtrebheeteae;brc(gahcaake)nssiwdnptgieohtvchepekoniebnwtta;uckd(racielen)larygws;iwtniphtehgoetwspiendtrmchoeredere;rauDgstcFiihtnn;iegogannepCdmroOo(fedd2rCug)gOicDnat2iFgso, npdtChriosOeesfs2ossCalugvOmrae2issp,seles prototroupdeens tihnetovtahlveepannedurmelaetaiscecthhaemsabmerpalen.d eventually wets the DF; and (d) DF dissolves to open the valve and release the sample
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